Noncellular rotary vacuum filter

ABSTRACT

A noncellular vacuum filter is provided in its interior with a blast chamber supplied with compressed air which is used for removing the filter cake from the outer circumference of a cylindrical filter drum. The blast chamber is formed by two telescoping sealing frames, both of which carry each a continuous flexible sealing bar extending all around the frames and which are adapted to engage the inner wall of the filter drum when the frames are radially moved outwardly by eccentrics on an eccentric shaft mounted in bearings carried by a baseplate closing the outer sealing frame opposite the side which has said sealing bar mounted thereon. A slot in the upper portion of the sealing bar attached to the inner sealing frame is in communication with apertures in said inner sealing frame so that compressed air from the blasting chamber is jetlike discharged and directed through the wall of the filter drum to remove the filter cake from the outer face of said drum.

United States Patent Heckmann Feb. 1, 1972 [72] Inventor: WolfgangHeckmann, Bergisch-Gladbach,

Germany [73] Assignee: Kiockner-llumboldt-Deutz Alrtiengesellschaft,Cologne-Mulheim, Germany [22] Filed: Apr. 23, 1970 [21] Appl.No.: 31,207

[30] Foreign Application Priority Data Apr. 29, 1969 Germany ..P 19 21717.5

[52] US. Cl. ..2l0l393, 210/402 [58] Field of Search ..210/39l-393, 402

[56] References Cited UNITED STATES PATENTS 916,481 3/1909 Noyes..210/391 X 2,352,303 6/1944 Young ..210/393 X FOREIGN PATENTS ORAPPLICATIONS 1,121,749 8/1956 France ....210/393 1,006,396 4/1957Germany ..2l0/393 Primary Examiner-John Adee v Attorney-Singer, Stern &Carlberg [57] ABSTRACT A noncellular vacuum filter is provided in itsinterior with a blast chamber supplied with compressed air which is usedfor removing the filter cake from the outer circumference of acylindrical filter drum. The blast chamber is formed by two telescopingsealing frames, both of which carry each a continuous flexible sealingbar extending all around the frames and which are adapted to engage theinner wall of the filter drum when the frames are radially movedoutwardly by eccentrics on an eccentric shaft mounted in bearingscarried by a baseplate closing the outer sealing frame opposite the sidewhich has said sealing bar mounted thereon. A slot in the upper portionof the sealing bar attached to the inner sealing frame is incommunication with apertures in said inner sealing frame so thatcompressed air from the blasting chamber is jetlike discharged anddirected through the wall of the filter drum to remove the filter cakefrom the outer face of said drum.

9 Claims, 2 Drawing Figures NONCELLULAR ROTARY VACUUM FILTER Theinvention relates to a noncellular rotary vacuum filter with a blastingchamber stationarily arranged in the interior of the filter drum, thewalls of said blasting chamber being sealed with respect to the innerchamber of the filter drum and discharging in the feed conduits for agaseous and/or liquid pressure and/or rinsing agent for blasting off thefilter cake and for the cleaning of the filter cloth.

The German Pat. No. 975,333 discloses already a noncellular rotaryvacuum filter, in which in the removal zone in the interior of the druma sealed chamber is arranged, which is provided with a frame-shapedsealing bar, which is pressed against the inner wall of the drum. Inthis chamber enter the feed conduits for a gaseous and/or liquidpressure or rinsing agent, respectively, for blasting ofi" the filtercake and if necessary for the cleaning of the filter cloth. In thisknown arrangement, the sealing bar and the drum wall, on account of thepressure force and the rotation of the filter drum undergo a constantwear, as the inner wall of the drum is never completely free fromadhering solid particles. In addition, the pressure force of the sealingbars require an additional expenditure of driving energy. With respectto the wear of the sealing bars, a relatively hard quality of rubbermust be selected, while the inner wall of the drum must not have anydepressions because the sealing bars, on account of their low elasticitywould not engage the wall sufficiently close to clean it. Thereforeeither a very accurately machined and therefore expensive inner wall ofthe drum is necessary, or one must be satisfied with a lower vacuum andwith a reduced yield of the filter.

The object of the invention is a noncellular rotary vacuum filter, inwhich the disadvantages of the known construction are prevented. This isaccomplished according to the invention, in that the wall of theblasting chamber has at least two sealing frames boxed into one another(or telescoped), elastically and gastight and connected with chamberparts, said sealing frames being provided on their side facing the drumwall each with a continuous elastic flexible sealing bar, and of whicheach is arranged movable in itself, and being in connection with aneccentric drive, in such manner, that the movement of both sealingframes takes place in the same direction and with a phase displacementof 360 times the number of the sealing frames.

The advantage of this arrangement is that during the rotation of thefilter drum, the sealing frames, on account of the movement in the samedirection and the phase displacement are alternatingly pressed againstthe inner wall of the drum. Apart from a low relative movement betweenthe drum wall and the sealing bar, in each case at the point of time ofengagement with the drum wall, no frictional strain takes place of thesealing bars. Therefore a wear of the sealing bars is prevented to afargoing extent. As for this reason substantially more elastic materialthan previously may be used for the sealing bars, the latter adhere verywell to the drum wall, so that a complete sealing effect is attained.

Of advantage in this connection it is to have the outer sealing frameconnected elastically and gastight with a stationary baseplate, and theinner sealing frames are in each case connected elastically and gastightwith the sealing frame surrounding them on the outside.

In developing the invention, it is recommended that in the blastingchamber an eccentric shaft connected with a motor is positioned with atleast one eccentric for each sealing frame, whereby the eccentric ineach case is arranged offset by 360 per number of the sealing frames,and is disposed in the as sociated sealing frame. This arrangementbrings it about that with a rotation of the eccentric shaft the sealingframes perform with reference to the axis of rotation of the eccentricshaft a translating circular movement, and as they are alternatinglypressed with elastic deformation of the sealing bar against the innerwall of the drum, they move the drum in direction of the rotation of theeccentric shaft, so as to effect simultaneously a rotation of the filterdrum.

In further developing the invention, it is suggested that for the feedof the pressure means for'blasting off the filter cake in the sealingbar of the inner sealing frame, which is disposed above the liquid levelof the trough filling, a slot is formed while in the sealing frameitself corresponding passage apertures are arranged. With such aconstruction, the feed of the pressure medium is advantageously limitedto a narrowly restricted space in the removal zone for the filter cakes,so that with small quantities of air at high 'speed, an effectiverelease of the filter cake is attained. As the slot is disposed in thesealing bar of the inner frame, the vacuum in the interior of the drumis effectively maintained with the aid of the outer movable sealingframe.

In a still further development of the invention, it is suggested thatthe baseplate, for the change in the pressure force of both sealingframes is adjustably slidably arranged in radial direction withreference to the axis of the filter drum. This construction has theadvantage, that in case of a standstill and pressure relief of thebaseplate of the blasting chamber, both sealing frames are lifted fromthe inner wall of the drum, so that the filter drum may be furtherrotated manually. A manhole is arranged in the usual manner in an endwall of the filter drum and therefore the interior of the drum is at alltimes accessible for carrying out any desired maintenance work therein.

In another embodiment of the invention it is suggested that the elasticseal between the outer sealing frame and the baseplate which is arrangedin the interior of the drum is constructed as a tube and that the tubebe connected by a supply or feed conduit with a source of pressureoutside of the drum filter. Also this development insures a change inthe contact pressure. Likewise it is possible after relief of the tubeto rotate the filter drum manually. With this embodiment, suitably thepositioning of the eccentric shaft on the baseplate is carried out withreference to the axis of the drum filter movably in radial direction, sothat the positioning of the eccentric shaft may be adapted to a slidablyshifting movement.

In addition, it is suitable to arrange in the feed conduit for theblasting air a valve which periodically opens and is so controlled bythe eccentric shaft, that the valve opens only then when the sealing barprovided with the slot engages the inner wall of the drum. Owing to thisprocedure, it is assured that when a high vacuum exists in the interiorof the drum, the compressed air ordinarily used for the blastingoperation cannot pass into the interior of the drum, when the contactpressure upon lifting one or the other sealing bar is lowered for ashort period of time.

With these and other objects in view, the invention will now be furtherdescribed with reference to the accompanying drawings which illustratesby way of example one preferred embodiment.

In the drawings:

FIG. 1 illustrates a vertical partial cross-sectional view of anoncellular rotary vacuum filter, and

FIG. 2 illustrates a horizontal longitudinal section along the line IIIIof FIG. 1.

Referring to FIG. 1, the perforated sieve drum 1, whose outer surface iscovered by a finely porous filter layer 2, made for example, of atextile fabric, is arranged approximately up to the one-half of its sizein a horizontal trough 3 filled with the sludge to be filtered. Abovethe upper edge of the trough wall and close to the outer drum wall,extends a discharge board 4, over which the filter cake on the outersurface of the drum blasted by compressed air coming from the inside ofthe drum is discharged. In order to make the blasting of the filter cakefrom the inside of the drum possible without the vacuum in the filterdrum being disturbed by the compressed air customarily used for theblasting operation, the removal zone must be sealed in the interior ofthe drum in the area of the compressed air feed from the vacuum chamber.For this purpose, according to the invention, there is secured on abaseplate 5, which is fixed to a stationary support 6 in the interior ofthe drum an outer sealing frame 8 with the intermediary arrangement of aframe-shaped elastic tube 7 connected with a source of pressure. Thesealing frame 8 is provided on its side facing the inner wall of thedrum with a continuous elastic sealing bar 9 along its entire edge.Within the sealing frame 8 is telescopically arranged an inner sealingframe 10, which is connected by another elastic tube seal 1 l with theouter sealing frame 8. On its side facing the inner wall of the drum,this sealing frame 10 is also provided with a continuous elastic sealingbar 12 extending along the entire edge of the frame 10.

According to FIG. 2 an eccentric shaft 13 is rotatably mounted parallelto the axis of the drum on the baseplate 5. This shaft 13 by way ofexample has arranged thereon two double-eccentrics l4, is, offset by 180to one another. The eccentric shaft in accordance with the invention, isradially movably relatively to the drum axis, namely in such manner,that the two axially spaced shaft bearings 16 are positioned each in alever 17, which is pivotally positioned in a bearing block 18 fixedlymounted on the baseplate 5. The eccentric 14 of the double-eccentricsconnected by a bearing with the sealing frame 8 and the eccentric isconnected by a bearing with the sealing frame 10. By means ofintermediate elastic couplings 19, the eccentric shaft is rotated insuitable manner by a hydraulic motor 20, which compared with anelectromotor has a higher reliability when arranged in the interior ofthe drum and permits in a simple manner a regulation of the number ofrevolutions. If new the hydraulic motor rotates the eccentric shaft,then both sealing frames described with reference to the axis ofrotation of the eccentric shaft a translatory circular movement, so thatthe sealing frames 8 and 10 are pressed with their sealing barsalternately against the inner wall of the drum. The baseplate of theentire arrangement is so adjusted that the elastic sealing bars in theirfarthest position in each case as compared with the inner wall of thedrum are evenly lifted. On account of the circular movement of the twosealing frames and the elastic deformation of their sealing bars, thedrum is accordingly set in rotation corresponding to the direction ofrotation of the eccentric shaft.

As shown in FIG. 1, the portion of the sealing bar 12 disposed above theliquid level of the sludge in the trough of the inner sealing frame 10is provided with a horizontal slot 21 extending over the entire lengthof the frame. The sealing frame itself is provided on its bearingsurface for the sealing bar with a plurality of apertures 22 inalignment with said slot 21. For the blasting of the filter cake,compressed air is admitted into the tubular drum shaft and from hereinto the inner part or interior of the drum. By means of a branchconduit, (not shown) this compressed air is then conducted through aninlet opening 23 in the baseplate 5 and into the sealed chamber formedwithin the sealing frames 8 and 10. From this chamber the compressed airpasses as a narrow jet extending over the entire length of the drumthrough the apertures 21 of the sealing frame 10 and then through theapertures of the filter drum, and blasts then the filter cake disposedon the exterior of the drum, so that it may run off over the dischargeboard 4.

The contact force necessary for the sealing operation may be adjusted byproviding the two tube seals 7 and 11 with separate feed conduits, whichintroduce a pressure medium from the outside, or the baseplate isarranged to be slidable as a whole in radial direction. This for examplemay be accomplished with the aid of a corresponding screw-threadedarrangement on the support 6 or by the intermediary connection ofhydraulic or pneumatic devices of known type.

What I claim is:

l. A noncellular rotary vacuum filter comprising a filter drum, meansforming a blasting chamber within said filter drum, said blastingchamber having walls which are sealed with respect to the interior ofthe filter drum, and conduits for a pressure medium used for blastingthe filter cake from the filter drum connected with said blastingchamber, wherein the improvement comprises that the walls of theblasting chamber are formed by at least two telescopically connectedouter and inner sealing frames between which are arranged elasticallyand gastight sealing means, said sealing frames being provided on theirside facing the inner wall of the drum each with acontinuous elasticflexible sealing bar, each of which is being arranged to be movable initself, and an eccentric drive (14, 15) connected with said sealingframes in such a manner that the movement of both sealing frames takesplace in the same direction and with a phase displacement of 360.

2. A noncellular rotary vacuum filter, according to claim I, in whichthe outer sealing frame is connected elastically and gastight with astationary baseplate and that the inner sealing frame is connectedelastically and gastight with the outer sealing frame which surroundsthe inner sealing frame.

3. A noncellular rotary vacuum filter according to claim 1 including aneccentric shaft arranged in the blasting chamber adjacent saidbaseplate, a motor connected with said eccentric shaft, said shaft beingprovided with at least one eccentric for each sealing frame, whereby theeccentrics in each case are arranged offset by 360 per number of thesealing frames and are positioned in the associated sealing frames.

4. A noncellular rotary vacuum filter according to claim 1, including aslot in a portion of said sealing bar for supplying the pressure mediumfor the blasting of the filter cake, said slot being disposed above theliquid level of the trough of the filter, said slot being incommunication with passages in said sealing frame, and said passagesbeing in communication with said blasting chamber.

5. A noncellular rotary vacuum filter, according to claim 1, in whichthe baseplate of the blasting chamber for the purpose of altering thecontact pressure of the sealing bars is arranged slidable in radialdirection of the filter drum.

6. A noncellular rotary vacuum filter, according to claim 2, in whichthe elastic connection between the outer sealing frame and thebaseplatecomprises a tubular member, said tubular member being connectedby a feed conduit with a source of pressure outside of the drum filter.

7. A noncellular rotary vacuum filter according to claim 3, includingspaced bearings for said eccentric shaft mounted fixedly on saidbaseplate.

8. A noncellular rotary vacuum filter according to claim 3, in whichsaid hydraulic motor for rotating said eccentric shaft is fixedlymounted on said baseplate.

9. A noncellular rotary vacuum filter according to claim 4, including afeed conduit supplying said blast chamber with a pressure medium and avalve in said feed conduit which is opened periodically, and is socontrolled that the valve opens only then when the sealing bar providedwith said slot engages the inner wall of said drum.

i i IF

1. A noncellular rotary vacuum filter comprising a filter drum, meansforming a blasting chamber within said filter drum, said blastingchamber having walls which are sealed with respect to the interior ofthe filter drum, and conduits for a pressure medium used for blastingthe filter cake from the filter drum connected with said blastingchamber, wherein the improvement comprises that the walls of theblasting chamber are formed by at least two telescopically connectedouter and inner sealing frames between which are arranged elasticallyand gastight sealing means, said sealing frames being provided on theirside facing the inner wall of the drum each with a continuous elasticflexible sealing bar, each of which is being arranged to be movable initself, and an eccentric drive (14, 15) connected with said sealingframes in such a manner that the movement of both sealing frames takesplace in the same direction and with a phase displacement of 360*.
 2. Anoncellular rotary vacuum filter, according to claim 1, in which theouter sealing frame is connected elastically and gastight with astationary baseplate and that the inner sealing frame is connectedelastically and gastight with the outer sealing frame which surroundsthe inner sealing frame.
 3. A noncellular rotary vacuum filter accordingto claim 1 including an eccentric shaft arranged in the blasting chamberadjacent said baseplate, a motor connected with said eccentric shaft,said shaft being provided with at least one eccentric for each sealingframe, whereby the eccentrics in each case are arranged offset by 360*per number of the sealing frames and are positioned in the associatedsealing frames.
 4. A noncellular rotary vacuum filter according to claim1, including a slot in a portion of said sealing bar for supplying thepressure medium for the blasting of the filter cake, said slot beingdisposed above the liquid level of the trough of the filter, said slotbeing in communication with passages in said sealing frame, and saidpassages being in communication with said blasting chamber.
 5. Anoncellular rotary vacuum filter, according to claim 1, in which thebaseplate of the blasting chamber fOr the purpose of altering thecontact pressure of the sealing bars is arranged slidable in radialdirection of the filter drum.
 6. A noncellular rotary vacuum filter,according to claim 2, in which the elastic connection between the outersealing frame and the baseplate comprises a tubular member, said tubularmember being connected by a feed conduit with a source of pressureoutside of the drum filter.
 7. A noncellular rotary vacuum filteraccording to claim 3, including spaced bearings for said eccentric shaftmounted fixedly on said baseplate.
 8. A noncellular rotary vacuum filteraccording to claim 3, in which said hydraulic motor for rotating saideccentric shaft is fixedly mounted on said baseplate.
 9. A noncellularrotary vacuum filter according to claim 4, including a feed conduitsupplying said blast chamber with a pressure medium and a valve in saidfeed conduit which is opened periodically, and is so controlled that thevalve opens only then when the sealing bar provided with said slotengages the inner wall of said drum.